As shown in FIG. 4, a conventional ultrasonic diagnostic system includes a two-dimensional array 107 in which a sub-array 105 composed of vibrators 101, 102, and a sub-array 106 composed of vibrators 103, 104 are arranged two-dimensionally. Received signals from the vibrators 101, 102 constituting the sub-array 105 respectively are input to amplifying sections 108, 109, and the amplifying sections 108, 109 output a non-inverted output signal (+) and an inverted output signal (−).
The non-inverted output signal (+) and the inverted output signal (−) output from the amplifying section 108 respectively are supplied to variable amplitude sections 110, 111 via a cross point switch 181. Furthermore, the non-inverted output signal (+) and the inverted output signal (−) output from the amplifying section 109 respectively are supplied to the variable amplitude sections 112, 113 via a cross point switch 191.
A signal output from the variable amplitude section 110 and a signal output from the variable amplitude section 112 are added to be input to a +45-degree phase shifter 114. Further, a signal output from the variable amplifier 111 and a signal output from the variable amplifier 113 are added to be input to a −45-degree phase shifter 115.
The output signals from the +45-degree phase shifter 114 and the −45-degree phase shifter 115 are added to be input to a main beam former 118.
As described above, the amplifying sections 108, 109, the cross point switches 181, 191, the variable amplitude sections 110, 111, 112, 113, the +45-degree phase shifter 114, and the −45-degree phase shifter 115 constitute a sub-beam former 116.
Furthermore, received signals from the vibrators 103, 104 constituting the sub-array 106 are input to a sub-beam former 117. It should be noted that the internal configuration of the sub-beam former 117 is the same as that of the sub-beam former 116. The signals output from the sub-beam formers 116 and 117 are subjected to delay addition by the main beam former 118, and are input to the signal processing section 119. The signal input to the signal processing section 119 is processed to be converted to an image signal, and displayed on a display section 120.
In the above-mentioned configuration of the sub-beam formers 116 and 117, the amplitudes of the received signals are controlled by the cross point switches 181, 191 and the variable amplitude sections 110 to 113, whereby the phases of the received signals are controlled, and the received signals from the vibrators in the sub-array are phased (e.g., see Patent document 1).
Patent document 1: U.S. Pat. No. 6,013,032 (col. 8-10, FIGS. 6, 7, and 9)